The present invention relates to the decontamination arts. It finds particular application as a composition to be used in conjunction with a liquid or dry sterilizing or disinfecting concentrate to form an environmentally friendly, microbicidally active solution containing peracetic acid with extended stability upon mixing with water and will be described with particular reference thereto. It should be appreciated, however, that the invention is also applicable to other liquid sterilization and disinfection processes where quantities of a decontaminant are to be used.
Disinfection connotes the absence of pathogenic life forms. Sterilization connotes the absence of all life forms, whether pathogenic or not. The term decontamination is used herein to connote sterilization, disinfection or other anti-microbial treatments.
Until recently, medical equipment and instruments were often decontaminated in a steam autoclave. Autoclaves kill life forms with a combination of high temperature and pressure. However, steam autoclaves have several drawbacks. The pressure vessels are often bulky and heavy. The high temperature and pressures used tend to curtail the useful life of endoscopes, rubber and plastic devices, lenses, and portions of devices made of polymeric materials and the like. Moreover, a typical autoclave decontaminating and cool down cycle is sufficiently long that multiple sets of the medical instruments are commonly required.
Liquid decontamination systems have been developed for equipment which can not withstand the high temperatures of steam decontamination. Traditionally, a technician mixed a liquid disinfectant or sterilant composition immediately prior to use and manually immersed the items to be decontaminated. More recently, automated decontamination systems have been developed in which a premeasured dose of a decontaminant in solution is circulated through the system. Examples of such systems are disclosed in U.S. Pat. Nos. 4,892,706 and 5,217,698. Items to be decontaminated are inserted into a receiving tray of the system and a cartridge of concentrated decontaminant inserted into a well. As water flows through the system, the decontaminant is diluted and carried to the receiving tray. At the end of a decontamination cycle, the decontaminant solution is disposed of and a fresh cartridge of the concentrated decontaminant is inserted into the system for the next cycle.
The decontaminant for the system may be formed from a liquid concentrate or a powdered composition. U.S. Pat. No. 5,007,008 discloses a liquid concentrate comprising peracetic acid. U.S. Pat. Nos. 5,116,575 and 5,350,563 disclose powdered anti-microbial compositions. The powdered anti-microbial compositions include two components which react in the presence of water to form a strong oxidant. Preferably, acetylsalicylic acid and a perborate, such as sodium perborate, are reacted to form peracetic acid. The powdered components further include surfactants, anti-corrosive materials, chelating agents, and buffers. The anti-corrosive materials inhibit corrosion of brass, copper, aluminum, steel, and other materials commonly found in medical, dental, and surgical instruments. The buffers, particularly phosphates, maintain the pH at around neutral and also act as anti-corrosives.
Liquid concentrates may be aspirated into the automated system from an ampule or capsule, as disclosed in U.S. Pat. No. 5,007,008. Powdered components are preferably stored separately until use. U.S. Pat. No. 5,662,866 to Siegel, et al. discloses a two-compartment cup which holds powdered components.
The present inventors have found that corrosion inhibitors containing heavy metals, such as molybdenum, tend to degrade the peracetic acid in the formulation during the decontamination process, contributing to a loss in effectiveness of the decontaminant solution.
Further, when large quantities of waste decontaminant solution are generated, the presence of some components, such as phosphates and heavy metals, in the waste may increase disposal costs. Environmental regulations often mandate maximum levels of heavy metals in waste waters and solid wastes. In the case of phosphates, the maximum levels have been reduced in recent years due to concerns that the biological oxygen demand of waters into which the wastes are released may become too high to support aquatic life. Sometimes, regulations require precipitation of waste water components.
An environmentally friendly decontaminant composition without phosphates would eliminate costly purification of the waste. Moreover, although phosphates in the waste precipitates can be used as fertilizers, the presence of certain heavy metals with the phosphates makes the precipitates undesirable for such a use. An environmentally friendly decontaminant composition without heavy metals would reduce costly purification of the waste.
The present invention provides for a new and improved decontaminant composition which overcomes the above-referenced problems and others.
In accordance with one aspect of the present invention, an environmentally-friendly composition which forms an effective decontaminant solution when mixed with an antimicrobial agent and water is provided. The composition includes a buffering system for buffering the pH of the decontaminant solution to a suitable pH for antimicrobial decontamination, the buffering system including at least one buffer selected from the group consisting of phosphates and zeolites and a corrosion inhibitor for inhibiting corrosion of metal components to be contacted by the decontaminant solution, the corrosion inhibitor being free of molybdenum and compounds thereof.
In accordance with another aspect of the present invention, a decontaminant solution with longer effective life is provided. The solution includes an antimicrobial agent and a buffering system which buffers the pH of the decontaminant solution to a suitable pH for antimicrobial decontamination. The buffering system including at least one buffer selected from the group consisting of phosphates and zeolites. The solution also includes a corrosion inhibitor for inhibiting corrosion of metal components to be contacted by the decontaminant solution. The corrosion inhibitor is free of molybdenum.
In accordance with another aspect of the present invention, a method of decontamination is provided. The method includes combining an antimicrobial agent and a composition with water to form a decontaminant solution. The composition includes a buffering system for buffering the pH of the decontaminant solution to a suitable pH for antimicrobial decontamination. The buffering system includes at least one buffer selected from the group consisting of phosphates and zeolites. The composition further includes a corrosion inhibitor for inhibiting corrosion of metal components to be contacted by the decontaminant solution, the corrosion inhibitor being free of molybdenum. The method further includes contacting items to be decontaminated with the solution for sufficient time to substantially antimicrobially decontaminate them.
In accordance with another aspect of the present invention, an environmentally-friendly composition which forms an effective decontaminant solution when mixed with an antimicrobial agent and water is provided. The composition includes a buffering system for buffering the pH of the decontaminant solution to a suitable pH for antimicrobial decontamination. The buffering system includes a zeolite. The composition also includes a corrosion inhibitor for inhibiting corrosion of metal components to be contacted by the decontaminant solution.
One advantage of the present invention is that the composition is environmentally friendly, facilitating disposal.
Another advantage of the present invention is that the composition is suited to formulation in both dry and liquid forms.
Still further advantages of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiments.